| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide the coder and the method for controlling code generation that avoid overflow of a transmission buffer effectively by preventing coded data amount from being increased unexpectedly. SOLUTION: A 1st mask circuit 54 is interposed in a path for generating conventional coded data in the coder 100, and a 2nd mask circuit 56 is provided to a path for motion vector information 34. When a data amount of a transmission buffer 12 reaches an upper threshold value, overflow of the transmission buffer 12 is expected and the processing of replacing substantial coded data with substitute data is started. The substitute data are coded data of a P picture resulting from zero-masking all quantization data by the 1st mask circuit 54 and applying zero-vector processing to a motion vector by a 2nd mask circuit 56, and the substitute data become short fixed length data through variable length coding. The replacement by using the substitute data is continued untill the data amount of the transmission buffer 12 reaches a lower threshold value at which no overflow occurs for the time being.</p> |
